1. Field of the Invention
The present invention relates to a sensor device, and more particularly to a sensor device and a manufacturing method thereof. The sensor device is integrated with an ultrasonic transducer and a microphone.
2. Description of Related Art
A conventional capacitive ultrasonic transducer has a substrate, a membrane, a first electrode and a second electrode. The substrate has a groove. The membrane is mounted on the substrate and covers the groove. The first electrode is mounted in the groove. The second electrode is mounted on the membrane and above the first electrode to form a capacitor structure. When the first electrode or the second electrode receives an AC (alternating current) signal, the membrane is then driven to vibrate in high frequency and create ultrasonic waves. Besides, the membrane can vibrate when the membrane receives environmental ultrasonic waves. Then the charge distribution on the electrodes changes to induce a capacitance variation. The capacitance variation can be used to perform position measurement, speed measurement or other physical measurements. However, the conventional capacitive ultrasonic transducer is adapted for ultrasonic frequency only, which cannot be used for sound frequency audible for humans. The function of the conventional capacitive ultrasonic transducer is thus limited.
A conventional capacitive microphone is adapted to sense sound waves audible for humans. However, the conventional ultrasonic transducer and the microphone are separate and independent components and are manufactured by totally different methods. In addition, the materials and the structures of them are different from each other.